The effect of cocaine on sperm motility characteristics and bovine cervical mucus penetration

Etiology of Male Infertility: an Update

Spermatogenesis is a complex process of germ cell division and differentiation that involves extensive cross-talk between the developing germ cells and the somatic testicular cells. Defective endocrine signaling and/or intrinsic defects within the testes can adversely affect spermatogenic progression, leading to subfertility/infertility. In recent years, male infertility has been recognized as a global public health concern, and research over the last few decades has elucidated the complex etiology of male infertility. Congenital reproductive abnormalities, genetic mutations, and endocrine/metabolic dysfunction have been demonstrated to be involved in infertility/subfertility in males. Furthermore, acquired factors like exposure to environmental toxicants and lifestyle-related disorders such as illicit use of psychoactive drugs have been shown to adversely affect spermatogenesis. Despite the large body of available scientific literature on the etiology of male infertility, a substantial proportion of infertility cases are idiopathic in nature, with no known cause. The inability to treat such idiopathic cases stems from poor knowledge about the complex regulation of spermatogenesis. Emerging scientific evidence indicates that defective functioning of testicular Sertoli cells (Sc) may be an underlying cause of infertility/subfertility in males. Sc plays an indispensable role in regulating spermatogenesis, and impaired functional maturation of Sc has been shown to affect fertility in animal models as well as humans, suggesting abnormal Sc as a potential underlying cause of reproductive insufficiency/failure in such cases of unexplained infertility. This review summarizes the major causes of infertility/subfertility in males, with an emphasis on infertility due to dysregulated Sc function.

Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality: A Study Among 1,215 Healthy Young Men

A total of 1,215 young Danish men aged 18-28 years were recruited between 2008 and 2012 when they attended a compulsory medical examination to determine their fitness for military service. The participants delivered a semen sample, had a blood sample drawn, and underwent a physical examination. They responded to questionnaires including information on marijuana and recreational drug use during the past 3 months (no use, use once per week or less, or use more than once per week). A total of 45% had smoked marijuana within the last 3 months. Regular marijuana smoking more than once per week was associated with a 28% (95% confidence interval (CI): -48, -1) lower sperm concentration and a 29% (95% CI: -46, -1) lower total sperm count after adjustment for confounders. The combined use of marijuana more than once per week and other recreational drugs reduced the sperm concentration by 52% (95% CI: -68, -27) and total sperm count by 55% (95% CI: -71, -31). Marijuana smokers had higher levels of testosterone within the same range as cigarette smokers. Our findings are of public interest as marijuana use is common and may be contributing to recent reports of poor semen quality.

Sperm parameters: paradigmatic index of good health and longevity

Since the discovery of spermatozoon by Anton van Leeuwenhoek in 1677, there has been an ever increasing understanding of its role in reproduction. Many factors adversely affect sperm quality, including varicocele, accessory gland infection, immunological factors, congenital abnormalities, and iatrogenic systemic and endocrine causes, such as diabetes mellitus, obesity, metabolic syndrome, and smoking. The mechanisms responsible for the association between poor sperm parameters and ill health may include oxidative stress, low-grade inflammation, low testosterone, and low sex-hormone-binding globulin. Oxidative stress in the testicular microenvironment may result in decreased spermatogenesis and sperm DNA damage, loss of sperm motility, and abnormal sperm morphology. Low testosterone caused by advanced age, visceral obesity, and inflammation is associated with the development of cardiovascular disease. Hence, semen analysis has an important role in the routine evaluation of idiopathic male infertility, usually manifested as low sperm counts, impaired sperm motility, or absence of sperm, and remains the most common single diagnostic tool. Several studies have shown an inverse relationship between semen quality and medical disorders. This review elucidates the effect of medical disorders and social habits on sperm quality, the mechanisms that are involved in the impairment of sperm quality, and whether or not sperm quality can be used as an index of good health and longevity in a man.

In guinea pig spermatozoa, the procaine-promoted synchronous acrosome reaction results in highly fertile cells exhibiting normal F-actin distribution

In guinea pig spermatozoa, procaine induces Ca(2+) independent hyperactivated motility suggestive of sperm capacitation. Nonetheless, in the presence of high extracellular Ca(2+), procaine increases cytoplasmic Ca(2+). We analyze the procaine effect on the acrosome reaction (AR) processes in guinea pig spermatozoa. Results indicated that: (i) in spermatozoa pre-incubated 5-30 min in MCM-PLG medium, procaine produced synchronous AR, (ii) the acrosome-reacted sperm number increased with the capacitation period before procaine treatment and with procaine concentration, (iii) acrosome reaction was blocked when Ca(2+) was omitted, (iv) plasma membrane-outer acrosomal membrane fusion started within 2 min after procaine treatment, (v) in acrosome-reacted spermatozoa, actin polymerization occurred and F-actin was located in the equatorial and post-acrosomal regions and (vi) procaine treatment resulted in highly fertile acrosome-reacted spermatozoa. This is the first report indicating that procaine promotes synchronic AR in mammalian spermatozoa. If procaine promotes premature AR of spermatozoa in vivo, it might be a factor for infertility in patients exposed to this local anesthetic.

The sperm, a neuron with a tail: 'neuronal' receptors in mammalian sperm

A number of plasma membrane receptor types originally thought to be specific to neurons have been found in other somatic cells. More surprisingly, the mammalian sperm and neuron appear to share many of these 'neuronal' receptors. The morphology, chromosome number, genomic activity, and functions of those two cell types are as unlike as any two cells in the body, but they both achieve their highly disparate goals with the aid of a number of the same receptors. Exocytosis in neurons and sperm is essential to the functions of these cells and is strongly influenced by similar receptors. 'Neuronal' receptor types in sperm may also play a role in the control of sperm motility (a function of course not shared by neurons). This review will consider the evidence for the presence of sperm plasma membrane 'neuronal' receptors and for their significance to mammalian sperm function. The persuasiveness of the evidence varies depending on the receptor being considered, but there is strong experimental support for the presence and importance of a number of 'neuronal' receptors in sperm.

Review: in vitro spermicidal tests

This review analyzes in vitro spermicidal tests that have been used to evaluate the spermicidal activity of contraceptive products. Special requirements and processes in numerous technologies were also reviewed. Nonoxynol-9 (N-9) was used as an example of a vaginally delivered spermicidal agent, and its spermicidal potency was compared by various spermicidal tests, such as Sander-Cramer, computer-assisted semen analysis, hypoosmotic swelling test, cervical mucus penetration test, and flow cytometry, and advantages and disadvantages of each test were specified. This provides an insight into the different aspects of sperm functionality on which each spermicidal agent exerts its activity. A rationale of the best combination of in vitro spermicidal tests, with particular emphasis on a simple and efficient strategy that targets the complete fertility control, was explained.

Characterization of in-vitro spermicidal activity of chelating agent against human sperm

The effect of ethylenediaminetetraacetic acid (EDTA), a cationic chelating agent, on sperm motility and sperm penetration through cervical mucus was evaluated. EDTA exerted a relatively mild dose-dependent effect on sperm motility. Total loss of sperm motility (EC100) was achieved at a concentration of about 5.0 mg/mL of EDTA, which is much greater than the 200 micrograms/mL concentration of Nonoxynol-9 (N-9). EDTA salts, such as EDTA-Na2 and EDTA-Na4, showed weak spermicidal activity, while EDTA-K2 and EDTA-Ca had no spermicidal activity at concentrations up to 5.0 mg/mL. EDTA appeared to decrease the in vitro percentage of motile sperm as a function of exposure time. EDTA completely impeded the penetration of sperm into cervical mucus at a concentration much lower than that for 100% inhibition of sperm motility in semen. In the presence of 500-3200 micrograms/mL extra calcium, the first-order rate constant for sperm immobilization, which was derived from the slopes of a relative sperm motility curve, was reduced by 38.9--55.6% of the control and was inversely proportional to calcium concentration. After exposure to EDTA, the calcium ion concentration in semen was reduced as a function of EDTA concentration, which yielded a linear reduction of sperm motility. A decrease of approximately 65% in calcium ion concentration in semen seemed to be the threshold at which total loss of sperm motility occurred. Calcium ion was shown to play an essential role in regulating sperm molitility in semen, and EDTA was demonstrated to exert spermicidal activity by modulating calcium ion concentration in semen.

Comparative in vitro spermicidal activity of chelating agents and synergistic effect with nonoxynol-9 on human sperm functionality

Nonoxynol-9 (N-9), a nonionic surfactant, exerts both spermicidal and anti-viral activities and is the most widely used spermicide. Although N-9 has been regarded as an efficient spermicidal agent for barrier contraception, it has been reported to cause vaginal irritation and allergic vaginitis, and its spermicidal action in the vaginal mucus may be limited. To address these problems, the spermicidal activity of several chelating agents against human semen and their synergistic effect on the spermicidal activity of N-9 were evaluated using computer-assisted semen analysis and a cervical mucus penetration test. Carbopol 934P, chosen as a polymer base for dispersion of N-9 and chelating agent, was also evaluated for its potential spermicidal activity. Chelating agents, such as ethylenediaminetetraacetic acid (EDTA), ethylene bis(oxyethylenenitrilo)tetraacetic acid, and gramicidin, had spermicidal activity against human sperm at the tested concentration range and exerted spermicidal activity within mucus, impeding sperm penetration to the extended cervical space. A synergistic effect was shown between N-9 and EDTA on sperm motility. In dose-response curves, 0.1% EDTA significantly increased binding affinity constant and spermicidal potency of N-9 and reduced the concentration of N-9 at which 50% of the maximum response was observed from 144.5 to 66.4 (micrograms/mL). A synergistic effect was also shown between EDTA and carbopol 934P polymer on inhibition of sperm penetration through the cervical mucus. Therefore, EDTA can be used as a supplementary agent and potentiator for N-9. Development of a carbopol 934P-based drug delivery system for dual controlled release of N-9 in combination with chelating agents seems to be a promising approach for increasing the efficacy of fertility control.

The effects of in vitro cocaine exposure on human sperm motility, intracellular calcium, and oocyte penetration

OBJECTIVE

To determine if cocaine exposure affects human sperm motility, intracellular calcium level, and fertilizing capability.

DESIGN AND METHODS

Human semen samples were treated with 1 to 1,000 microM cocaine hydrochloride for up to 2 hours in vitro. Sperm motion kinematics were measured by computer-assisted semen analysis (CASA). Spermatozoan intracellular calcium was determined by laser cytometry. The sperm fertilizing capability was assessed using the zona-free hamster oocyte penetration test.

RESULTS

After a short exposure (15 minutes) to cocaine, the sperm motion kinematic parameters, straight line velocity and linearity, were decreased in the high concentration groups. However, after a longer exposure (2 hours) to cocaine, the differences were no longer significant. Cocaine treatment did not alter spermatozoa intracellular calcium levels. Most importantly, human sperm treated with cocaine at a high concentration were fully capable of penetrating zona-free hamster oocytes.

CONCLUSION

Human spermatozoa acutely exposed to high concentrations of cocaine initially demonstrate a decrease in two motion kinematics, straight line velocity and linearity. However, overall, cocaine exposure had no significant effects on sperm motility and fertilizing capability.